Carbonization of old shale in a compact moving solids bed



July 18, 1961 E. v. MURPHREE CARBONIZATION OF OLD SHALE IN A COMPACTMOVING SOLIDS BED Filed March 20, 1958 3 Sheets-Sheet 1 TO PRODUCT 24RECOVERY RAW SHALE SEPARATOR GAS SEPARATO FIGURE I Eger V. MdrphreeInventor By M? Attorney July 18, 1961 E. v. MURPHREE CARBONIZATION OFOLD SHALE IN A COMPACT MOVING SOLIDS BED FiledMarch 20, 1958 3Sheets-Sheet. 3

RAW SHALE Y m m M R T G ow a M a m E 7.. m n m n w 4. s w H 78 6S F m EE N 0 m N 0 Z N 0 MN MW 3 K m SGT WE S 6 m A WDM H 0 M M U o m w P R k wc P m w B tw w 0 n O 2 8 W fi 9 5 SEPARATOR Inventor t Eger V. MurphreeFIGURE 11 M27? Attorney United States Patent i 2,992,975 CARBONIZATIONOF OLD SHALE IN A COMPACT MOVING SQLIDS BED Eger V. Murphree, Summit,N.J., assign'or to Esso Research and Engineering Company, a corporationof Delaware Filed Mar. 20, 1958, Ser. No. 722,744 '17 Claims. (Cl.202-6) The present invention is concerned with the treatment ofoil-bearing solids, such as shale and other oil-bearing sands and/orminerals. More particularly, it deals with supplying heat to a retortingsystem by the application of entrainable hot, fine particles propelledas a gaseous suspension passing through a column of relatively coarseshale particles.

The present invention is a continuationdn-part of System for RecoveringOil from Solid Oil-Bearing Materials, S.N. 564,938, and now US. PatentNo. 2,908,617, by the present inventor, filed February 13, 1956.

As is well known in the art, the recovery of oil from shale and similaroil-bearing materials requires pyrolitically treating the solids tobreak down their oil-forming matter, kerogens and the like. Hydrocarbonsof suitable molecular weight and structure to find application as rawpetroleum fractions are thus released. Generally, temperatures in therange of 7001800 F. or higher, preferably between 800-1200 F., have beenfound suitable for effecting this result. The released hydrocarbons arewithdrawn either as vaporous material or as condensed liquid products.

Numerous modes of operation have been advanced for retorting oil shale.For example, it has previously been suggested to burn the carbonaceousresidue on the spent shale solids, and thereafter introduce the hot fluegases formed into the retorting zone. Further, previous processes suchas Peck, US. Patent 2,480,670, have employed shale as a heat transferagent. Additionally, the use of large sized solid heat-carrying medium,i.e., shot, is known in the art.

However, the prior art systems have suffered from several fairlyimportant disadvantages. In several previous proposals employingrelatively fixed, non-turbulent shale solids flow, good heat transferhas been dificult to obtain. It has been felt that to have trulyeffective thermal conduction and highly turbulent mixing, fluid bedoperations might be required. But proper fluidization of a solids massso as to give the pseudo-liquid phase characteristic of a true fluid bedoperation requires that the solids be of rather fine size, e.g.preferably below 1000 microns. Since oil-bearing solids such as shale,when withdrawn from natural deposits, are of the order of 0.25 toseveral inches in diameter, an expensive and cumbersome comminutionoperation may be necessitated. As is well appreciated by those skilledin the art, an appreciable size reduction step applied to thousands oftons of solids is an exceedingly costly operation. Moreover, since afluid bed is essentially a single stage heat transfer zone, operating atsubstantially a single temperature, the beneficial aspects ofcounter-current heat exchange may not be realized.

The present invention sets forth a system whereby relatively coarseshale solids may be efiiciently subjected to preheating, retorting andcombustion.

More particularly, the oil-shale is rctorted by flowing the shale solidsas a relatively compact, moving solids column, e.g. void space of about50%, counter-current to a gaseous suspension of hot entrainable solids.Both the advantages of truly counter-current flow heat treatment andfluidized solids operation are simultaneously obtained. Each of the hot,entrainable solid particles effectively sees a given horizontal sectionof the shale column only once as it passes through the interstices ofthe coarse shale Z,lid2,975 Patented July 18, 1961 bed. Nevertheless,there is intimate contact between the fine and coarse solids, thusinsuring good solid-solid heat transfer. The actual velocity ofpropellant gas will, of course, depend upon the particle size anddensity of the fine solids utilized. Further, since thesuspension-propellant gas utilized for conveying the fine solidparticles will normally be at an elevated temperature, approximatelyequal to that of the solids, additional gas-solids heat exchange isrealized.

It should be noted that the fine solids pass through and out of theshale column as a relatively dilute, rapidly flowing suspension. Therelatively high interstitial velocity of the suspension, preferablyranging between 4 to 10 ft./sec. or greater, insures that no fines willbe lost at the lower end of the treating zone along with downwardlymoving coarse shale. The actual gas velocity employed is dependent uponthe particle size and density of the fine solids used as the heatcarrier media. Since large quantities of shale must be treated per unitof oil recovered, even a small percentage of fines carried along withthe shale would result in excessive fine particle losses. Moreover, therapidly flowing gases serve to sweep liberated oil from the surface ofthe shale solids, thereby serving to promote the thermal treatment ofthe kerogen constituents.

The use of a fairly rapidly moving solids-gas suspension to heat a shalecolumn may be utilized for accomplishing any, or all, of the basic heattreatment steps in the retorting system. It may advantageously be usedfor the heat treatment operations of preheating the raw shale feed,retorting, transferring sensible heat from a combustion zone to otherprocessing regions, recovering heat from spent shale, etc. Whilecounter-current flow of fine and coarse solids is preferred, the use oftransverse, or even co-current flow, should be construed as fallingwithin the scope of the present invention.

With regards to fine solids suitable as heat transfer media, generallyany relatively fine particle entrainable in a gas stream is suitable.Particles of less than about 1000 microns in diameter, preferably below500 microns, are preferred. Among solids suitable are sand, ceramicmaterials, glass beads, spent shale fines, carbonaceous solids, metallicparticles, etc. If desired, solid particles having catalytic propertiesmay be utilized.

The various aspects of the present invention will become more clearlyapparent by referring to the following description, examples, andaccompanying drawings.

FIGURE I illustrates a system wherein a single vessel unit is employedfor effecting retorting, fine solids being passed into the retortingzone along with the combustion gases.

FIGURE II depicts a particularly advantageous procedure wherein productoil contamination may be kept at a minimum.

FIGURE III shows an alternative mode of operation employing a separate,fine solids heating vessel.

Turning to FIGURE I, there is shown unitary reaction vessel 10. Withinvessel 10, there is successively maintained preheating zone 11,retorting zone 12, combustion zone 13, and generally spent shale coolingzone 14. While the following description of this embodiment of thepresent invention is directed to a single vessel shell, multiplevessels, as in FIGURE III, may be adapted for this type of operation.

As indicated, relatively coarse, raw shale enters the upper portion 16of vessel Ill by means of funnel-shaped member 15 or other suitableintroduction means. The shale, generally at ambient temperature, willnormally range in size from about 0.25 to 5 or more inches in diameter,and is introduced in amounts sufficient to form a relatively compact,freely moving coarse shale column progressively passing through the heattreating zones.

Oxygen-containing gas such as air is introduced into the lowermostsection of combustion zone 13 and/or the upper portion of shale coolingzone 14 by distributor 34. Entrainable fine solids, preferably suspendedin a propellant gas introduced through line 33, are injected into theair-preheating or shale cooling zone by conduit 19, the fine solidshaving previously been separated from overhead gases as will be latermade more apparent.

In addition to air, other gases such as light hydrocarbons, make-gasfrom the retorting system, flue gas, inerts, or the like, may beinjected into the lower section of vessel 10, thereby serving as acarrier gas and a means of independently controlling the oxygen supplyand heat capacity of the gases introduced into the system. If desired, asubstantial amount of combustible gas may be added to the combustionzone or below. It has been found that greater heat efficiency may berealized by injecting the air some distance above the point ofintroduction of the fines and carrier gases to the shale cooling zone.By thus limiting rapid ignition of recycle gases, increased heatrecovery is realized in the shale cooling zone. However, if desired, theair may be introduced into a lower portion of the vessel, as forexample, into cooling zone 14.

Generally, a major portion of the non-oxygen gases are introduced intoshale discharge conduit 17 by line 37, thus upwardly removing finesolids from the descending shale lumps. By blowing fines from the spentshale, the fine solids inventory is kept relatively constant.

Various means can be used to introduce gases and fine solids, and toremove shale from the bottom of the column. One method, which is shownin the drawings, involves the use of a conical grid 20 operating inconjunction with shaker bars 35. The fine solids suspension is thusevenly distributed upwardly through the descending, moving bed of largerparticles while permitting continuous withdrawal of the spent shalethrough outlet conduit 17. The downward movement of the shale iscontrolled by shaker bars 35 or other similar devices, and by means ofvalve 18 located in the solids discharge line. Of course, other methodswell known to those skilled in the art of solids handling, fortransferring solids out of the vessel may be alternatively employed.

The gases and fine solid particles are introduced at proper ratios so asto form an upwardly moving solidsgas suspension having a loadingdensity, for example, in the range of 0.1 to 3.0 lbs/cu. ft., andtraveling at an interstitial velocity in excess of 6 ft./sec. The spentshale is thus cooled to a temperature of the order of below 300 F.

The preheated suspension then passes into combustion zone 13 whereincarbonaceous material on the spent shale leaving the retorting zone isoxidized, substantially consuming all the oxygen. Generally, the solidssuspension is thereby heated to temperatures greater than 1000 F. Theentire hot, upflowing mass of fine solids, combustion flue gas,propellant gas, etc. then enters retorting zone 12 wherein it serves tosupply the requisite thermal energy for the retorting step itself. Theheavy oil-containing kerogen material is thu pyrolized and lighter oilfractions liberated. A retorting temperature in the neighborhood of 1000F. is normally preferred.

In order to avoid condensation of desired oil products on the coarseshale descending from the preheating zone, the upflowing eflluent of theretorting Zone is removed from vessel 10. The drawing indicates ahorizontal series of funnel-like entrances 21 leading into withdrawalconduit 22 for passage to separator 23. Of course, numerous otherdevices such as a partition element may be used to effect withdrawal ofupflowing gas-solids stream.

Separator '23 removes the fine solids from the mixture of product oiland flue gas. The gases are then passed by line 24 to suitable recoverymeans, such as a fractionator or the like, wherein desired oil productsare sep arated from the flue gases. Fine solids are recirculated 4through standpipe 25, line 28, and injection means 29 for additionalheat exchange in shale preheating zone 11. After recovery of the oilproduct, the flue gas drawn off the top of the retorting zone isreturned to the vessel 10 by line 36. The flue gas also preferablyserves as an aeration gas for conveying fine solids, by being introducedthrough lines 26 and 27. The re-IniXing of fine particles and flue gasmay be readily performed before, or after, the flue gas is introducedinto the reaction vessel 10.

The gas-solids suspension then continues up into the preheating zone 11,therein giving up its heat to shale passing downwardly. Raw shale maythus be preheated to temperatures in excess of 550 F.

The suspension is thereafter withdrawn from vessel 10 through outlet 30,and passed to separator 31, which may be one or more cyclones or otherconventional units. Separated, relatively cool flue gas may be thendischarged to the atmosphere through line 32, or preferably at least aportion thereof recycled to the retort. Additionally, it could be usedas a fuel gas since this stream will contain some light ends from theretorting operation. Alternatively the light ends might be recovered assuch. Normally, it is desirable to recirculate at least the majorportion of fine solids to the lower sect-ion of the reaction Vessel 10by means of line 19. Of course, a fine solids purge or fresh solidsintroduction line may be installed wherever desired in the fine particlecycle.

Broadly, FIGURE I is illustrative of a system employing the concept ofthe present invention wherein both fine entrainable solids andcombustion flue gas are passed through the retorting zone. Whilenumerous modifications of this system may be made, for example, asregards to the specific structure of vessel 10, precise point of solidsand gas introduction and withdrawal, etc, they are to be construed asfalling within the present teachings.

Referring to FIGURE ii, there is shown another mode of operation inaccordance with the present invention. FIGURE II differs from FIGURE Iin that at least a portion of the flue gas emanating from the combustionzone is withdrawn from the system so as not to be passed into theretorting section. Since more air is required to furnish heat than isnecessary for the formation of an upflowing fine solids-gas suspension,there would otherwise be excessive product contaminating gases ascompared to that required for propelling the hot, fine solids throughthe retorting zone. Thus, by withdrawing flue gases, the amount of gasesin the higher section of the retort is decreased, and hence the amountof vapors that have to be cooled down and separated from desired oilproducts is reduced.

Basically, the system consists of a preheating zone 51, retorting zone52 and a combustion and gas preheating zone 53. Separate vessels may beused to form one or more of these zones, although a single shell system50, as illustrated, is normally preferred. Deflector 84 is pro vided todistribute the raw shale across the preheating zone. Similar devices maybe used at the entranceway to the other treating sections. As shown,each zone terminates in a funnel-shaped member, eg 72, 70, leading intothe zone below. As previously described, raw shale is introduced intothe upper portion of the system and flows downwardly as a moving solidscolumn. Other means of substantially horizontal, or even upward,movement of the shale column may be utilized.

The shale holdup is controlled by valve 57 and the rate of initial shalesolids introduction. If desired, bafiles and the like may be inserted inthe central portion of the various treating sections as a means ofincreasing solids holdup time.

Fine, en-trainable particles, either as recovered from the effluent ofthe preheating zone or from an external source, are introduced into zone53 by line 53. Propellant gas such as inerts, hydrocarbons, recoveredflue gas,

make gas from product recovery, etc. injected by line 59 serves as aconveying medium. As in FIGURE I, a substantial portion of the carriergases is introduced into shale withdrawal conduit 56 by line 85 as ameans of stripping fines from the spent shale column. Oxygencontaininggas such as air is introduced into the lower portion of the combustionzone and/or the upper section of the gas preheat section by inlet 60. Asshown, the inlets terminate in gas dispersion means 61 which may takethe form of nozzles, grids, etc. Of course, added diluent gas may beutilized. The coarse shale column flows downwardly through exit 56whencefrom it may be totally discarded, stored, or burned as fuelmaterial.

The heat of the spent shale serves to preheat the fine solids suspensionto combustion temperatures, the oxidation of carbonaceous spent shaleresidue and combustible injected gases providing the basic thermalenergy for the retorting step. Thereafter, the mixture of hot flue gasand fine solids is Withdrawn overhead by line 63 and passed to separator64. Baflie elements 62 and 71 are advantageously provided in the upperportion of the treating zone so as to guide fine solids flow, reducedead gas spaces, and limit erosion of structural walls. After separationand removal of flue gases by line 65, entrainable fines are thencirculated through line 66 into the retorting zone. Conveying gas,introduced by lines 68, and 67, serves 'as a transporting medium and asa means of forming the requisite hot, fine particle suspension.

The drawing illustrates at least a portion of the flue gas beinginjected into the retorting zone by one or more lines 67 and 69, thustaking advantage of its sensible heat. However, it may be desired toavoid any recirculation of flue gas to the retorting section, so as tominiimize problems in recovering released oil products.

The suspension of hot, fine solids passes upwardly through the retortingsection between the interstices of the downwardly moving coarse shalecolumn, and is withdrawn overhead through exit passageway 73 togetherwith liberated shale oil fractions. Hot fine solids are re covered andrecirculated to preheating zone 51 by line 76 along with propellantgases introduced through taps 77, 78 and line 79. It may be desirable touse additional hot flue gas for this purpose, although other gaseousmaterials may be readily applied. Additionally, only the hot flue gas(no hot fines) may be used for the preheating step. Separated oilconstituents are withdrawn from separator 74 by line 75 and passed toproduct recovery steps as is well known in the art.

In the preheating zone, additional counter-current heat exchange isefiected. Raw shale passes down entranceway 55 into zone 51, wherein itis contacted with the hot, solids suspension, thereafter flowing intothe retorting zone 52.

The cooled suspension is then withdrawn through outlet 80 and passed toseparator 81 wherein fine solids are recovered, the gas stream beingnormally vented to the atmosphere. Fine particles are returned throughdipleg 83 and line 58 into zone 53, as previously described.

'I hus, oil shale may be effectively heated with a minimum of productoil contamination.

With reference to FIGURE III, illustrated is a system differing fromthat previously described in that the fine, entrainable solids to beused as heat-carrying medium are heated in an external heater vessel103, and are never subjected to the combustion reaction of the spentshale in burner vessel 102.

As shown, the system consists primarily of preheater 100, retort 101,burner 102, and solids heater 103. Coarse shale is passed, preferably bymeans of gravity flow, successively through preheating, retorting andoxidation steps in the form of a moving packed bed. It should, however,be understood that all the procedures heretofore described could beoperated in somewhat different manners while still employing the basicinventive concept of the present invention. For instance, a moving beltor chain grate might be utilized for aiding shale flow. Alternatively,the reaction vessel might take the form of a rotating chamber.

In the specific embodiment illustrated, raw oil shale is introduced intopreheater vessel through entranceway 105, and flows continuouslydownward through columns 107 and 109 into the several treating zones.The treating vessels preferably contain shaker bars or distributingstructures 106, 108 and 110 for insuring uniform continuous solids flow.Valve 111 provides a means of controlling shale solids buildup. Whilethe shale treating vessels are shown as individual units, a commoncircumsciibing shell structure may unite the preheating, retorting andcombustion vessels into a single unit.

Counter-current to the spent shale moving through burner 102, air orother oxygen-containing gas is introduced between the combustion andshale cooling zones by means of inlet 116. It may be desirable torecirculate a portion of the off-gases from preheater 100 or othergasesous media injected by line 115, through conduit 114 as a means ofindependently varying oxygen and overall gas rates. Conduit 114 isadvantageously branched so as to ensure suflicient aeration of thedischarging shale column, and stripping of fines therefrom.

The injected gases are preheated to combustion temperatures by contactwith spent shale, and thereafter serve to oxidize the carbonaceous shaleresidue fractions. Hot flue gas is circulated through conduit 112 tosolid heater 103 wherein there is maintained a mass of fine solidparticles, e.g. sand. Heater 103 preferably has a distribution grid 113or the like for uniformly contacting the flue gas and time solids. Theheater may be operated as a fluid bed, transfer line, staged bed,raining solids zone, etc., in order to promote eflicient heat transfer.Suflicient heat is conveyed to normally raise the temperature of theentrainables to above 1000 F.

While not illustrated, requisite heat for the overall system may besupplied in whole or in part by combustion of a gaseous fuel such as themake-gas from the retorting operation, or extraneous hydrocarbons. Forexample, the combustion of shale residue may be entirely eliminated, andan auxiliary gas burner, supplied with fuel and oxygen, used in itsplace. The hot flue gases from the gas burner may be passed into and.through the solids heater 103 in much the same flow pattern as describedin reference to the flue gas of vessel 102. Alternatively, solids heater103 may itself operate as a combustion zone, combustible gases and airbeing supplied thereto in amounts to heat the fine solids tosufficiently high temperatures so as to enable them to supply therequired thermal energy for the retorting process. Both the systems ofFIGURE I and FIGURE II may be similarly adapted so that the combustionof fuel gases, e.g. recycle make-gas, rather than the spent shaleprovides the heat for the overall process. By burning fuels other thanoil-shale, the shale is never exposed to high combustion temperatures,and thus heat consuming carbonate decomposition may be kept at a minimumconsistent with good oil recovery. Additionally, non-combusted shale isof greater strength, and has less of a tendency to decrepitate than doesshale from Which carbon has been removed. This means that highfines-suspension velocities can be used in the retorting zone sincethere is a decreased tendency for shale decrepitation into finesparticles which might be entrained in the heat-carrying fine solidsstream.

Returning to FIGURE III, the partially cooled flue gas, after havingentrained solids removed in separator 117, is then passed through line118 into preheater '100 wherein it additionally serves to preheat theraw shale. Multiple injection distributor 119 extending over the majorportion of the cross section of vessel 100, is employed to insure goodgas-solids contact across the full volume of the unit. The distributormay take the form of a group of pipes disposed in parallel fashion, thepipes having gas ejection holes at their lower surfaces. Other devicesfor uniform contacting of gases with solids, such as a grid arrangement,bubblecap type distributor, etc., could alternatively be employed. Thecooled flue gas is then withdrawn overhead through exit passageway 120.It may be thereafter immediately discharged from the system by line 132.Normally, after purging or removing part of the flue gas from line 122by means of line 123, the rest of the gas is recirculated through lines124- and 114 back to the burner vessel 102. The drawing illustrates theuse of a separator 121 in the path of the flue gas flow. Such amodification may be desirable when fine shale particles are suitable forserving as the heat transferring entrainable solids, the fines beingformed in the preheater by the abrasion and decrepitation of the coarseshale solids. Separated fines may be then passed into the solids heater103 by conduit 125. Additionally, it should be understood that finesolids may be directly employed as a means of preheating the coarseshale.

Turning to the operation of the retorting vessel 101, preheated coarseshale entering the unit by passageway 107 flows downwardly in the formof a moving solids column. A portion of the hot, fine heat-carryingparticles is circulated to the retort by line 126, propellant gas beingintroduced by line 127 in sufiicient amounts to form a gas-solidssuspension of relatively high, e.g. about 10 ft./sec., interstitialvelocity. Additional propellant gas may be injected by line 128. Thefine solids thus pass upwardly through the downwardly moving courseshale bed, supplying sufi'lcient heat thereto to liberate contained oilconstituents. The fines and oil products are moved overhead by exit 129and circulated to separator 130. De-entrained solids are returned to theheater 103, separated hydrocarbons being sent by line 131 to additionalproduct recovery steps, not shown.

The use of an external heater for the fine solids is advantageous inthat the solids are not subjected to the high temperature combustionzone, wherein decrepitation and occlusion of waste materials tends tooccur. Further, there is no problem of distributing solids through thecombustion zone, and generally, the use of a closed solids circuit willbring fine solids losses to a minimum.

Table I below presents a compilation of pertinent data applicable to thepresent invention.

Table I Broad Preferred Example Range Range Temperature Conditions:

Raw Shale Inlet Temp., F. -500 50-100 70 Preheated Shale Temp, F.300-800 550-750 650 Retort Temp, F 700-2, 500 800-1, 200 1,000Combustion Temp, F 1, 000-2, 500 1, 200-1, 600 1,300 Fine Solids Temp.Upon Entering Retorting Zone, F 1 000-2, 500 1, 000-1, 300 l, 150 SolidsCharacteristics:

Average Diameter of Raw Shale, Inches. 0. -8 0. 25-5. 0 2.0 AverageDiameter of Fine Solids, microns 0-1, 000 40-500 100 Bed Conditions:

Bulk Density of Shale C01- umn, lbs/it. 30-110 60-90 75 Loading Densityof Fine Solids Suspension, lbs./ ft. 1 0. 02-5. 0 0.1-3.0 2.0 MinimumInterstitial Velocity of Fine Solids Suspension, ftJsec 3.0 4.0 10.0

1 Loading density being defined as the ratio of pounds of entrainablesolids introduced/standard cubic feet of carrier gas passing through thetreating zone, both taken for a given time interval.

It should be clearly understood that various modifications may be madeto the present invention. Distribution means such as grids, baffles,nozzles or the like may be provided to insure good distribution of thefine solids suspension across the coarse shale column and to controlsolids holdup. Additionally, individual features discussed in connectionwith any of the illustrated systems may be applied to modifying othersystems described. Basically, the present invention teaches supplyingheat to a column of oil-bearing material by the use of a suspension ofhot, entrainable solids, and is, as far as the art permits, to beconstrued as applying to all variations of this fundamental concept.

Having described the invention, what is claimed is as follows:

1. In a process for recovering oil from an oil-bearing solid shalematerial wherein said oil-bearing solid shale material is transported asa downwardly moving solids bed, the method of effecting heat treatmentof said oilbearing shale solids which comprises introducing a suspensionof entrainable fine solid particles and propellant fluid into the bottomportion of said bed for upward passage therethrough, said fine solidparticles being at a higher temperature than said oil-bearing shalesolids and passing said fine solid particles in fluid suspensionupwardly through and out of said bed thereby ettecting heat treatment.

-2. The method of claim 1 where said oil-bearing shale material isrelatively coarse shale ranging in size from 0.25 to 5 inches indiameter and said entrainable fine solid particles are sand ranging from40-500 microns in size.

3. A process for recovering oil from oil-bearing shale solids whichcomprises the steps of preheating said shale solids in a preheatingzone, passing the thus preheated solids in the form of a downwardlymoving compact solids column into a retorting zone wherein they areretorted by countercurrent contact with an upwardly flowing hot gaseoussuspension of fine entrainable solids, removing oil vapor from saidretorting zone, continuing the downward passage of said oil-bearingsolids, withdrawing at least a portion of said gaseous suspension ofentrainable solids from said moving solids column in said preheatingzone and separating said entrainable solids, subjecting said separatedentrainable solids to heating in a heating zone, and circulating thethus heated entrainable solids to further contact said moving solidscolumn in said retorting zone.

4. The process of claim 3 where said oil-bearing solids are heated in apreheating zone by contact with gaseous effluent of a combustionreaction.

5. The process of .claim 3 wherein said entrainable solids are heated ina burning zone, heat being generated by the combustion of carbonaceousmatter of spent oilbearing solids.

6. The process of claim 3 wherein said entrainable solids are heated ina heating zone by means of the thermal energy liberated by the oxidationof a combustib'le gas.

7. A process according to claim 3 wherein said gaseous suspension ofentrainable solids is withdrawn from the upper portion of saidpreheating zone.

8. A process according to claim 7 wherein said withdrawn gaseoussuspension is heated in a combustion zone below and in communicationwith said retorting zone and said heated gaseous suspension is passedupwardly through said retorting zone.

9. A method for retorting oil-bearing solids which comprisesprogressively passing said solids as a gravity flowing moving compactbed downwardly through a preheating zone and a retorting zonecountercurrent to an upflowing gaseous suspension of hot entrainablesolids, heat for said preheating and retorting zones being supplied bysaid entrainable solids, said entrainable solids having been previouslyheated by means of the combustion of a combustible gas.

10. A thermal process for recovering oil from oilbearing shale solidswhich comprises flowing relatively coarse oil-bearing shale solids as adownwardly moving compact bed progressively through a preheating zone,retonting zone, and combustion zone, passing an oxygencontaining gasinto said combustion zone so as to burn off carbonaceous residue on saidoil-bearing solids, withdrawing hot flue gas produced thereby andpassing said flue gas to a separate heating zone containing a mass offine solids so as to heat said solids, introducing at least a portion ofsaid heated fine solids from said heating zone into said retorting zonein the form of an upflowing gaseous suspension so as to supply thermalenergy for the retorting operation, removing oil vapors from saidretorting zone, withdrawing said gaseous suspension of fine solids fromsaid retorting zone, and separating at least a portion of said finesolids and returning it to said heating zone.

11. The process of claim wherein at least a portion of the partiallycooled flue gas is further circulated from said separate heating zone tosaid preheating zone for additional thermal exchange.

12. The process of claim 10 wherein at least a portion of said finesolids from said heating zone is passed through said preheating zone inthe form of a gaseous suspension thus supplying heat thereto.

13. A process for recovering oil from shale particles which comprisesfeeding shale particles to the upper portion of a preheating zone,preheating the shale particles in said preheating zone, passing thepreheated shale particles into a retorting zone and then to a combustionzone, said zones being arranged one above the other in the order named,said shale particles moving downwardly through said zones as a movingbed, passing a gaseous suspension of fine entrainable solids upwardlythrough said zones in countercurrent flow tosaid moving bed of shaleparticles, introducing air into said combustion zone for upward passagetherethrough and for burning carbonaceous residue from spent shaleparticles moving from said retorting zone to and through said combustionzone, said gaseous suspension of fine entrainable solids being heated inpassing upwardly through said combustion zone, passing said heatedgaseous suspension of fine entrainable solids upwardly through saidretorting zone to heat the shale particles and to remove oil from saidshale particles, removing oil vapors and entrained solids from saidretonting zone, passing the hot gaseous suspension of fine entrainablesolids upwardly through said preheating zone, removing the gaseoussuspension of fine entrainable solids from the upper portion of saidpreheating zone, and removing cooled spent snale particles from thebottom portion of said combustion zone.

14. A process according to claim 13 wherein fine entrained solids areseparated from said gaseous suspension removed from the upper portion ofsaid preheating zone and the separated fine solids are returned to saidcombustion zone below the region of introduction of the air.

15. A process according to claim 13 wherein the solids entrained in theoil vapors are removed and returned to the lower portion of saidpreheating zone.

16. Apparatus for recovering oil from relatively coarse oil-bearingsolids which comprises, in combination, a re tort vessel, a preheatingvessel above said retort vessel, 3; fine solids heating vessel, feedmeans for introducing oilbearing solids into said preheating vessel,means for passing preheated coarse solids from said preheating vesselinto said retort vessel in the form of a downwardly moving bed, meansfor maintaining a mass of entrainable fine solids in said heatingvessel, means for withdrawing said entrainable solids from said heatingvessel and for introducing a gaseous suspension of said entrainablesolids into said retort vessel, removal means for withdrawing gaseousmaterial from said retorting vessel and separation means for separatingentrained solids therefrom, conduit means for returning at least aportion of said separated solids to said heating vessel, passage meansfor removing said oil-bearing solids from said retort vessel, acombustion unit, means for supplying fuel and oxygen-containing gas tosaid combustion unit and conduit means for passing hot flue gas fromsaid combustion unit to said heating vessel.

17. Apparatus according to claim 16 wherein said heating vessel is acombustion zone, and which further comprises conduit means forintroducing a combustible fuel material and an oxygen-containing gas tosaid heating vessel.

References Cited in the file of this patent UNITED STATES PATENTS2,480,670 Peck Aug. 30, 1949 2,680,091 Barr et al June 1, 1954 2,710,828Scott June 14, 1955 2,776,935 Jahnig et a1. Jan. 8, 1957 2,889,267 Barret a1. a- June 2, 1959 UNITED STATES PATENTOFFICE CERTIFICATE OFCORRECTION Patent No. 2,992,975 v July 18, 1961 Eger V. Murphree It ishereby certified that error appears in the above numbered petentrequiring correction and that the said Letters Patent should read ascorrected below.

In the heading to the printed specification, line 2, in the title ofinvention, for "OLD" read OIL in the heading to the drawings, Sheets 1,2 and 3, in the title of invention, for "OLD" read OIL Signed and sealedthis 2nd day of January 1962.,

(SEAL) Attest:

ERNEST W, SWIDER DAVID L. LADD At t e s t 1 ng Of 1? 1 c e rCommissioner f Patents

1. IN A PROCESS FOR RECOVERING OIL FROM AN OIL-BEARING SOLID SHALEMATERIAL WHEREIN SAID OIL-BEARING SOLID SHALE MATERIAL IS TRANSPORTED ASA DOWNWARDLY MOVING SOLIDS BED, THE METHOD OF EFFECTING HEAT TREATMENTOF SAID OILBEARING SHALE SOLIDS WHICH COMPRISES INTRODUCING A SUSPENSIONOF ENTRAINABLE FINE SOLID PARTICLES AND PROPELLANT FLUID INTO THE BOTTOMPORTION OF SAID BED FOR UPWARD PASSAGE THERETHROUGH, SAID FINE SOLIDPARTICLES BEING AT A HIGHER TEMPERATURE THAN SAID OIL-BEARING SHALESOLIDS AND PASSING SAID FINE SOLID PARTICLES IN FLUID SUSPENSIONUPWARDLY THROUGH AND OUT OF SAID BED THEREBY EFFECTING HEAT TREATMENT.